γ-MnOOH-graphene nanocomposite as promising anode material for Li-ion capacitors

Abstract

Developing environmentally benign electrode materials with faster Li-ion kinetics is an essential requirement for high-performance Li-based energy storage devices. Here we report the large-scale synthesis of γ-MnOOH-graphene (γ-MnOOH-rGO) nanocomposite, through a simple hydrothermal route, for their application as potential anode material in Li-ion batteries. As-synthesized nanocomposite with the γ-MnOOH nanorods uniformly anchored on the graphene sheets exhibits enhanced electrochemical performance and achieves a very high specific capacity of ∼435 mAh g−1 at a current density of 1.0 A g−1. Detailed electrochemical studies reveal faster Li-ion kinetics in γ-MnOOH-rGO nanocomposite electrode, dominated by non-diffusion controlled processes (∼ 80% at 1.0 mV s−1). Further, the full-cell Li-ion capacitor fabricated with γ-MnOOH-rGO nanocomposite as the anode and activated carbon as the cathode exhibits a maximum energy density of ∼51 Wh kg−1 and a maximum power density of ∼ 6.3 kW kg−1, with excellent capacity retention of more than ∼87% upon 8500 cycles. The present work thus demonstrates γ-MnOOH-graphene nanocomposite as promising anode material for advanced Li-ion batteries and high power Li-ion capacitors.